(a) Field of the Invention
The present invention relates to a liquid crystal display.
(b) Description of the Related Art
An LCD includes two panels having pixel electrodes and a common electrode, and a liquid crystal (LC) layer with dielectric anisotropy that is interposed between the two panels. The pixel electrodes are arranged in a matrix and connected to switching elements such as thin film transistors (TFTs) that supply them with data voltages. The common electrode covers substantially the entire surface of one of the two panels and is supplied with a common voltage. The pixel electrode, the common electrode, and the LC layer form an LC capacitor. The LC capacitor is a basic element of a pixel along with the switching element connected thereto.
In the LCD, the pixel electrode and the common electrode generate an electric field in the LC layer when a voltage is applied. Light transmittance through the LC layer is adjusted by controlling the strength of the electric field, thereby obtaining desired images.
The display device receives digital input image data for primary colors such as red, green, and blue from an external graphics source. A signal controller of the display device appropriately processes the input image data and supplies the processed image data to a data driver implemented as an IC (integrated circuit) chip, etc. The data driver converts the digital image data into analog data voltages and applies the data voltages to the pixels.
Often, the bit number of the input image data from the graphics source does not match that of the image data that can be processed by the data driver. For example, a data driver that is capable of processing only 10-bit data is commonly used for reducing the manufacturing cost when the bit number of the input image data is thirteen.
In order to convert the 13-bit image data into the 10-bit image data that is capable of being processed by the data driver, it is proposed that dithering be applied for use in the display device. The dithering represents high-bit data as low-bit data, and translates their temporal and spatial arrangements to fit the 10-bit data format. During the dithering process, the signal controller modifies high-bit input data in a frame for a pixel into low-bit data depending on the position of the pixel and the serial number of the frame. This modification is done according to the dithering data pattern stored in a memory such as a frame memory. Dithering data pattern includes the pattern to be used to modify data as a function of the position of the pixel and the serial number of the frame.
Manufacturing cost is decreased by using the dithering data patterns. However, as there are fewer number of bits that represent grays of images, color reproducibility is compromised. The decreased number of gray levels results in a decreased number of colors represented.